1. Field of the Invention
The present invention relates generally to memory cards, and more particularly to a memory card (e.g., a multi-media card or secure digital card) comprising a flexible substrate (a “flex”) which is integrated in the memory card and folded in a prescribed manner subsequent to having various active and passive devices (e.g., controller and memory devices) surface mounted thereto for purposes of providing the memory card with increased capacity.
2. Description of the Related Art
As is well known in the electronics industry, memory cards are being used in increasing numbers to provide memory storage and other electronic functions for devices such as digital cameras, MP3 players, cellular phones, and personal digital assistants. In this regard, memory cards are provided in various formats, including multi-media cards and secure digital cards.
Many memory cards include a module which itself comprises a printed circuit board (PCB) having a conductive wiring pattern disposed thereon. Attached to one side or surface of the PCB and electrically connected to the conductive pattern thereof is a plurality of electronic circuit devices, such as semiconductor packages, semiconductor dies, and/or passive elements. These electronic circuit devices and a portion of the PCB are often covered or encapsulated by an encapsulant material. The PCB also includes a plurality of input/output (I/O) pads or external signal contacts (ESCs) disposed on the side or surface thereof opposite that having the electronic circuit devices thereon. These contacts are not covered by the encapsulant material, and thus are exposed in the completed module which comprises the PCB, the electronic circuit devices and the encapsulant material. Attached to the module is a skin or case of the memory card, such case generally defining the outer appearance of the memory card. The module is coupled to the case such that the contacts disposed on the PCB are not covered by the case, and thus remain exposed in the fully assembled memory card. These contacts of the memory card provide an external interface for an insertion point or socket. The completed memory card has a generally rectangular configuration, with most memory cards including a chamfer formed at one edge thereof which is adjacent to the contacts. In an effort to simplify the process steps needed to fabricate the memory card, there has been developed various memory cards wherein the case is eliminated by applying the encapsulant material the electronic devices and to the PCB such that the encapsulant material hardens into a cover or body of the memory card which is sized and configured to meet or achieve a desired “form factor” for the memory card.
Memory cards, as currently known, have a prescribed data storage capacity, such capacity corresponding to the electronic circuit devices integrated into the module. In conventional memory cards, the electronic circuit devices of the module include controllers and memory devices which store data and output it under the control of the controller. Since mobile devices such as digital cameras, digital camcorders, MP3 players and telecommunication devices need more data to implement various functions and services, there has been a corresponding increase in the need for increased data storage capacity in relation to the memory cards used in such mobile devices. At the current pace of technological development, the necessary data storage capacity of memory cards is doubling approximately every six months.
The present invention addresses the need for memory cards of increased capacity by providing a memory card comprising a flexible substrate (a “flex”) which is integrated in the memory card and folded in a prescribed manner subsequent to having various active and passive devices (e.g., controller and memory devices) surface mounted thereto. The use of folded flex technology in the memory card of the present invention allows the same to support four or more standard, pre-packaged memory devices, thus providing the memory card with substantially increased capacity. These and other attributes of the present invention will be described in more detail below.